DESCRIPTION

Note on ISO-2022-JP(-1)?

ISO-2022-JP-1 (RFC2237) is a superset of ISO-2022-JP (RFC1468) which
adds support for JIS X 0212-1990. That means you can use the same
code to decode to utf8 but not vice versa.

$utf8 = decode('iso-2022-jp-1',$stream);

and

$utf8 = decode('iso-2022-jp',$stream);

yield the same result but

$with_0212 = encode('iso-2022-jp-1',$utf8);

is now different from

$without_0212 = encode('iso-2022-jp',$utf8);

In the latter case, characters that map to 0212 are first converted
to U+3013 (0xA2AE in EUC-JP; a white square also known as 'Tofu' or
'geta mark') then fed to the decoding engine. U+FFFD is not used,
in order to preserve text layout as much as possible.

BUGS

The ASCII region (0x00-0x7f) is preserved for all encodings, even
though this conflicts with mappings by the Unicode Consortium. See